Answer:
The combined cost of 1 pound of salmon and 1 pound of swordfish is $16.66
Step-by-step explanation:
Let us assume the cost of 1 pound salmon = $ m
So the cost of 1 pound of 1 pound swordfish cat = $ ( m - 0.20)
Now, the Amount of salmon purchased = 2 1/2 pounds
So, the amount of salmon purchased = 2.5 pounds
Cost of buying 2.5 pounds = 2.5 x ( 1 pound cost)
= 2.5 ( m) = $ 2.5 m ...... (1)
Also, the Amount of swordfish purchased = 1 1/4 pounds
So, the amount of swordfish purchased = 1.25 pounds
Cost of buying 1.25 pounds = 1.25 x ( 1 pound cost of swordfish)
= 1.25 ( m - 0.20) = $ 1.25 m - 0.25 .... (2)
Now, the combined cost paid = $ 31.25
⇒Cost of buying (2.5 pounds salmon + 1.25 pounds swordfish) = $ 31.25
or, 2.5 m + 1.25 m - 0.25 = 31.35 (from (1) and (2))
or, 3.75 m = 31.60
or, m = 31.60/3.75 = 8.43
⇒ m = $8.43
So, the cost of 1 pound salmon = m = $8.43
and the cost of 1 pound swordfish = m - 0.20 = $8.43 - 0.20 = $ 8.23
Hence, the combined cost 1 pound of salmon and 1 pound of swordfish = $8.43 + $ 8.23 = $ 16.66