Answer:
$2.70
Explanation
Jennifer and Linda both bought one apple, but they bought different numbers of oranges. Looking at the numbers, we see that Linda bought 2 more oranges than Jennifer (they bought the same number of apples, so disregard apples for now, we will look at them later).
Subtracting Jennifer's cost from Linda's cost, 7.50 - 5.10 = 2.40
So, we know that 2 oranges cost $2.40, so 1 orange will then cost $1.20.
Now we know the cost of 1 orange. So, we can find the price of an apple by finding the cost of 3 oranges. 3 x 1.20 = 3.60. So, Jennifer's 3 oranges cost 3.60, and subtract this cost from the total cost and we find that 1 apple costs $1.50.
Add the price of 1 apple and 1 orange. $1.50 + $1.20 = $2.70