Oscar bought some mangosteens and coconuts in the ratio of 2 : 5 respectively. The cost of a mangosteen was $1.50 more than the cost of a coconut. He spent a total of $81 buying the mangosteens and coconuts. The total cost of the coconuts was $9 more than the total cost of the mangosteens. How much did 1 mangosteen cost?
If there are 2x mangos and they cost y dollars each, then
2xy + 5x(y-150) = 81
5x(y-150) = 2xy + 9
now solve to get x=6 and y = 3
check:
2*6=12 mangos at $3 each cost $36
5*6=30 nuts at $1.50 each cost $45
36+45 = 81
45 = 36+9