Answer:
C
Explanation:
let x be number of adults and y the number of underage , then
x + y = 350 → (1)
6x + 4y = 1600 → (2)
multiplying (1) by - 4 and adding to (2) will eliminate y
- 4x - 4y = - 1400 → (3)
add (2) and (3) term by term to eliminate y
(6x - 4x) + (4y - 4y) = 1600 - 1400
2x + 0 = 200
2x = 200 ( divide both sides by 2 )
x = 100
the number of adults who attended is 100