Question

Sally Pays £25 for two tubes of paint a blue tube and a red tube. the blue tube cost £7 more than the red tube.

Answer 1

Let's say the price of the red tube is x, and the price of the blue tube is x + 7. Then the total cost 25 is the price of the red tube plus that of the blue tube, or x + x + 7.

$2x+7=25 \\ 2x =18 \\ x=9$

The red tube cost £9, and the blue tube cost £16.