http://prntscr.com/ldmkiy

Hard to see, but it looks like 1/4 of her spending was on petrol

if 1/4 = 25 (90 degrees on the pie chart)

Then her total spending was 4 x L25 = L100

She spent $25 on petrol....the central angle of the petrol sector = 90°

So....this must represent 1/4 of the circle since the whole circle measures 360°

So.....she must have spent 4 times $ 25 = $100