Hi
Let x be a pizza's cost and y the sandwich cost
3x + 4y = $34
3x + 7y = $41.50
Multiply 1st EQ by -1 to eliminate x
-3x - 4y = -34
3x + 7y = 41.50
3y = 7.50
y = $2.50 and x = $8.00
Checking our answer
3x + 7y = $41.50 = $24 + $17.50
Wish You the Best in your Studies.
3P + 4S = 34
3P + 7S = 41.50
----------------
3S = 7.50 << subtracted 1st eqn from 2nd eqn
S = 2.50 --> P = 8.00