Subjects

The student makes a mathematical task for five minutes and the task from biology in twelve minutes. On another day, he has homework in math and biology, which consists of eleven tasks together. To do the job took an hour and a half. How many tasks are made in each subject?

Correct answer:

b =  5
m =  6

Step-by-step explanation:

5m+12b = 1.5·60
m+b=11

5·m+12·b = 1.5·60
m+b=11

12b+5m = 90
b+m = 11

Row 2 - 1/12 · Row 1 → Row 2
12b+5m = 90
0.58m = 3.5


m = 3.5/0.58333333 = 6
b = 90-5m/12 = 90-5 · 6/12 = 5

b = 5
m = 6

Our linear equations calculator calculates it.

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