HermionePct

Let x be the original price of the mangoes.
Let y be the original amount of mangoes.

xy=60---(i)
(x+1)(y-2)=60---(ii)

In (i),
xy=60
y=60/x---(iii)

Sub (iii) into (ii)
(x+1)(60/x-2)=60
x=5 or -6(rejected)

Therefore, the original price of each mango is $5.

HermionePct

Let x be the original number of boxes used.
Let y be the original no of cups one box contains.

xy=120---(i)
(x-3)(y+2)=120---(ii)

In (i),
xy=120
y=120/x---(iii)

Sub (iii) into (ii)
(x-3)(120/x+2)=120
x=15 or -12

Therefore, the original no of boxes used is 15.