Work hourly wage, percentage increase The wage of jack is increased by 15% and at the same time, the working hours is decreased by 10%. Then, by what percent the hourly wage of jack is decreased or increased? (approximately) I tried $\frac{\frac{1.15w}{.9h}-\frac{w}{h}}{\frac{w}{h}}$. Where am I going wrong? The answer is increase of 28%. Please explain.

I'm assuming Wage = Hourly Wage $\times$ Hours

You could say $$W=hw\times h\\\W+15\%=hw\times (h-10\%)\\\1.15=hw\times .90\\\hw=1.28$$

This is saying the Wage went up by 0.15, the hours went down by 0.10 and the hourly wage went up by 0.28

EDIT: I bet this makes more sense. $$hw_{old}=\frac{W}{h}\\\hw_{new}=\frac{1.15W}{0.9h}\\\\\frac{hw_{new}}{hw_{old}}=\frac{\frac{1.15W}{0.9h}}{\frac{W}{h}}=1.28$$

Maybe where you went wrong was subtracting out the $\frac{W}{h}$ in the middle of the expression instead of subtracting $1$ from $1.28$?