Answer:
Peter got 15/20 and Thando got 7/10 and mary got 17/25
to compare fractions which do not have the same denominator:
We reduce them to the same denominator, the largest is the one with the largest numerator
Peter got 15/20 and Thando got 7/10 and Mary got 17/25 to justify who got the higher score
common denominator: 100
Peter: (15*5)/20*5 = 75/100
Thando: (7*10)/(10*10)= 70/100
Mary:(17*4)/(25*4)=68/100
Peter got the highest score