Solving One-Step Equations (Subtraction) | Algebraic Equations | Math with Mr. J

welcome to math with Mr J [Music] in this video I'm going to cover how to solve One Step subtraction equations now when we solve one step equations we want to isolate the variable which means get it by itself basically we want to undo whatever is being done to the variable that way the variable is by itself on one side of the equation we do this by using the inverse or opposite operation keep in mind it is very important that whatever is done to one side of the equation it must be done to the other that keeps everything balanced and equal let's jump into number one where we have y minus 21 equals 43. now we need to isolate that variable of Y we need to figure out what y equals since 21 is being subtracted from y we need to undo that subtraction by using the inverse operation so the opposite operation the opposite of subtraction is addition so let's add 21 to the left side of the equation now whatever we do to one side of the equation we must do to the other in order to keep it balanced and equal so we need to add 21 to the right side as well now let's take a look at the left side of the equation we are subtracting 21 and adding 21. so these 21s cancel out they equal zero so our variable Y is now isolated it's by itself so y equals and then on the right side of the equation 43 plus 21 equals 64. so why equals 64. that's our solution now we can always check a solution by plugging it into the original equation so let's plug 64 in for y and see if this works 64. minus 21 equals 43. 64 minus 21 does equal 43 so we have the correct solution y equals 64. let's move on to number two where we have 90 equals g minus 15. we need to isolate that variable of G 15 is being subtracted from G so we need to undo that subtraction by using the inverse operation the inverse of subtraction is addition so let's add 15 to the right side of the equation now whatever we do to one side of the equation we must do to the other so let's add 15 to this side as well now on the right side of the equation we are subtracting 15 and adding 15. so these 15s cancel out they equal zero so G is now isolated it's by itself g equals and then on the left side of the equation 90 plus 15 equals 105. so g equals 105 and we can rewrite this with the variable coming first and that is our solution now let's check that Solution by plugging 105 in 4G and seeing if this works so 90 equals 105 minus 15. 105 minus 15 does equal 90 so our solution is correct g equals 105. so there you have it there's how you solve One Step subtraction equations I hope that helped thanks so much for watching until next time peace