Answer:
612 students and 325 adults
Step-by-step explanation:
I'll use substitution for this set of equations. I'll start with 2a + 0.75s = 1,109.
2a + 0.75s = 1,109
Subtract 0.75s from both sides.
2a = -0.75s + 1109
Divide both sides by 2.
a = 1/2(-3/4s + 1109)
Make 1/2(-3/4s + 1109) into a single fraction
a = -3/8s + 1109/2
Substitute -3/8s + 1109/2 for a in the other equation (a + s = 937).
-3/8s + 1109/2 + s = 937
Add -3/8s to s.
5/8s + 1109/2 = 937
Subtract 1109/2 from both sides.
5/8s = 765/2
Multiply both sides by 8/5, the reciprocal of 5/8.
s = 612
Now head back to the original equation, and substitute s for 612.
a = -3/8 * 612 + 1109/2
Multiply -3/8 by 612.
a = (-459 + 1109)/2
Add 1109 to -459 and divide by 2.
a = 650/2
a = 325
The system is solved. There are 612 students and 325 adults.