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The senior classes at High School A and High School B planned separate trips to New York City. The senior class at High School A rented and filled 1 van and 6 buses with 372 students. High School B rented and filled 4 vans and 12 buses with 780 students. Each can and each bus carried the same number of students. How many students can a van carry? How many students can a bus carry?
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Your equations are
1*v + 6*b = 372, (1)
4*v + 12*b = 780, (2)
where v is a van capacity and b is a bus capacity.
Now express v = 372 - 6b from (1) and substitute it into (2). In this way you exclude v and obtain a single equation for b:
4*(372-6b) + 12b = 780.
Can you complete the solution on your own?