Each pen costs 3 times as much as each eraser. If the total cost of two pens and four erasers is 6.30, find the cost of each pen.

X is the cost of the eraser.

2 (3x) + 4x = 6.30

10x = 6.30 ~ Divide each side by 10.

x = 0.63

Then multiply 0.63 by 3 to get the cost of the pen which is

0.63 x 3 = $1.89

The cost of each pen is $1.89

The cost of each eraser is 0.63 cents.