Please tell me how to find the answer step by step

Question

Rick and Casey are buying fish at the local market for their restaurants. Rick buys 5 brook trout for x dollars each and 2 rainbow trout for y dollars each and pays $160 for the fish. Casey buys 3 brook trout for x dollars each and 4 rainbow trout for y dollars each and pays $194 for the fish. The system of equations shown below represents this situation.

Which statement is true?

 A. 

Rick spent more money on rainbow trout than he did on brook trout.

 B. 

Casey paid $18 for each rainbow trout.

 C. 

A rainbow trout costs $17 more than a brook trout.

 D. 

Casey spent 3 times as much on brook trout than he did on rainbow trout.

Answer 1

A is true, Rick spent more on rainbow trout than brook trout. 90>70

B is true. Casey paid $18 for each rainbow trout.

15x+20y+970 3 times 5x+2y=160

15x+6y=480 5 times 3x + 4y= 96

Subtract equations to get

14y=490 divide by 14

y=35

5x+2(35)=160 substitute 35 for y

5x=90 x=18

x is 18 for both Rick or Casey

C is wrong, as rainbow trout cost $17 less not more than brook trout.

D is wrong. Casey spent less than 3 times as much on brook as rainbow trout. 130 is less than 3 times 54.