Jerry F. answered 02/05/23
Compassionate teacher of math & physics (for a few decades)
Let A be the number of adult tickets, C be the number of children tickets. Then the following equations result:
A+C = 1900 [1] and
42A+22C = 63800 [2].
Solve [1]: C = 1900-A . Substitute for C in [2]: 42A + 22(1900-A) = 63800.
Solve for A: 42A+(22)(1900)-22A = 63800
42A - 22A = 63000 - (22)(1900)
20A = 63800-41800 = 22000
A = 22000/20 = 1100, which gives C = 1900-1100 = 800
Check solution: (100)(42) + (800)(22) = 63800.
Jerry F.
Another example of: two independent equations, that can be solved for two unknown quantities.02/05/23