Answer:
The value of x is 3.
Explanation:
Matthew earned 7500 of 15000, which is exactly half the total amount, meaning that the fraction corresponding to his earnings is 1/2.
Rate of 5:2:x, with number 5 corresponding to Matthew, mean that his fraction of the earnings, in function of x is given by:
![(5)/(5 + 2 + x) = (5)/(7 + x)](https://img.qammunity.org/2022/formulas/mathematics/college/a7jh2d3wc5z9wxo1xw0gczmctkhmd0i4ge.png)
Both fractions are equal, so:
![(5)/(7 + x) = (1)/(2)](https://img.qammunity.org/2022/formulas/mathematics/college/gbh69v88w9qpsdmx95q0murdv016efth6y.png)
Applying cross multiplication:
![7 + x = 10](https://img.qammunity.org/2022/formulas/mathematics/college/zog5dtpuertt7ejwmeoymnnc2tj5g21djr.png)
![x = 10 - 7](https://img.qammunity.org/2022/formulas/mathematics/college/wclqhk17jbwkw016401kysa7oubim7mpnp.png)
![x = 3](https://img.qammunity.org/2022/formulas/mathematics/high-school/yir5wqailux3q9a06dvay00xbhx6pnj4w0.png)
The value of x is 3.