Let x be the number.
Set up an equation:
2x - 2/3x = 20
Simplify:
1 1/3x = 20
Divide both sides by 1 1/3
X = 15
The number is 15
It should be " b "
That should be right but u may want to wait for others to respond to this to make sure
Using a system of equations, the prices are given as follows:
<h3>What is a system of equations?</h3>
A system of equations is when two or more variables are related, and equations are built to find the values of each variable.
For this problem, the variables are given as follows:
- Variable x: Cost of a reference book.
- Variable y: Cost of an exercise book.
3 reference and 2 exercise cost RM63, hence:
3x + 2y = 63.
5 reference and 3 exercise cost RM102, hence:
5x + 3y = 102.
Multiplying the first equation by 3 and the second by -2, we have that:
Adding them:
-x = -15 -> x = 15.
Hence:
3(15) + 2y = 63
2y = 18.
y = 9.
Hence the costs are:
More can be learned about a system of equations at brainly.com/question/24342899
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