(a) let's write an equation to solve this problem.
Let's let w be the total number of watermelons and m be the total number of mangoes.
Using the problem, we have the system of equations
w=m+132/5w=4/9m
Subsituting out w with m from the first equation, we get
25(m+13)=49m
Solving this equation yields
m=117. Since there are 13 more watermelons, then w=130
Next, let's find how many of each there were. Since 2/5(130)=52, we have
52∗2=104
So 104 is our final answer.
Thanks! :)