Let us say that:
o = cost of oranges per pound
p = cost of pears per pound
so that:
o = p – 2
Therefore:
10o + 8p = 61
10 (p – 2) + 8p = 61
10p – 20 + 8p = 61
18p = 81
p = 4.5
p = $4.5 per pound
So 3 pounds of pears would cost:
total cost = 3 * 4.5
total cost = $13.5