The weight in 1980 is 
kilograms
<em><u>Solution:</u></em>
From 1980 to 1990, Lior’s weight increased by 25%
His weight is "k" kilograms in 1990
<em><u>To find: weight in 1980</u></em>
This is a percentage increase problem
Let "x" be the weight in kilograms in 1980
<em><u>The percentage increase is given by formula:</u></em>
Here,
Initial value in 1980 = x
Final value in 1990 = k
Percentage increase = 25 %
<em><u>Substituting the values in formula,</u></em>
Thus the weight in kilograms in 1980 is
My teacher told be to try and think of it as a circle, because circles are 360 degrees. Then to place those angles in the circle and it should make it easier to find the angles, because when you see it in the circle, you can divide it into 4 parts so that you would then have 4, 90 degree angles that you can then work off of by placing those angles you need to find into the circle. It was supposed to make it easier, and i genuinely hope that you can do this. You got this, and you will get through the pain of math tonight and many more. Good luck. ^-^
