Mathematics
Easy

Question

# The cost of 4 pens and 4 pencil boxes is \$100. Three times the cost of a pen is \$15 more than the cost of a pencil box. The cost of a pen and a pencil box respectively are

## \$15 and \$8\$10 and \$15\$12 and \$10 \$16 and \$12 Hint:

## The correct answer is: \$10 and \$15

### Here we have to find that the cost of Pen and pencil,Firstly , it is given at the cost of 4 pens and 4 pencil is \$100 .Lets pen be x and pencil be y respectively,So , 4x + 4y = 100 Dividing by 4 both sides, x + y = 25        ----(1)And also 3 times cost of pen is \$15 more than cost of a pencil box, so we can write,3x = 15 + y 3x – y = 15      ----(2)Adding eq(1) and eq(2), we get… x + y = 25+ 3x – y =15----------------------  4x = 40   x = 10substitute x = 10 in eq( 1) 10 + y = 25 y = 25 – 10 y = 15Therefore , The cost of Pen and pencil \$10 and \$15.Or simply,Let the cost of a pen and a pencil be x and y respectively.4x+4y=100x+y=25    ...(1)3x=y+153x−y=15    ...(2)Adding (1) and (2), we get4x=40x=10Substitute x=10 in equation (1) to get y=15

In this question, we have to make equation on the given date about ages. For making equations , considers the variable of given data and make more than 1 equation to solve.

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