Problem Solving

[grand belfry]

You could say that x is the number of students who solved the first problem, y is the number that solved the second, and t is the total number of students

x/t = 0.7

y/t = 0.60

x + y - 9 = t

[foggy spire]

solve for x and y in the first two equations, and plug them in to the third and solve for t

[pallid coyote]

Is 60 the answer

[austere slate]

.close