Answer:
80 kg
Explanation:
Change the 10% to a decimal so we can work with it in an equation. 10% is .10 (move the decimal two places to the left).
The new weight is 88kg. Let's let the beginning weight be called x.
x = beginning weight
New weight = beginning weight + weight gain
88 = x + .10x
Combine like terms.
88 = 1.10x
Divide by 1.10
88/1.10 = 1.10x/1.10
80 = x
The beginning weight was 80 kg