Question 763476
Children = x
Adults = y
x + y = 754...1
1.50x + 2.25y = 1422...2
Multiply (1) by 2.25
2.25x + 2.25y = 1696.50...3
1.50x + 2.25y = 1422...2
Subtract (2) from (3)
0.75x         = 274.50
    x         = 366
Substitute x = 366 in (1)
x + y = 754
366 + y = 754
      y = 388
366 children and 388 adults swam at the pool.
Hope this helps.
:-)