Answer:
1 tea: £1.20
1 coffee: £1.50
Step-by-step explanation:
Let's t represent teas and c represent coffees; we have the equations
2t + 3c = 6.90
4t + 7c = 15.30
We multiply the first equation by -2
-4t - 6c = -13.80
4t + 7c = 15.30
c = £1.50
Now we put 1.50 in for c and find the price for one tea.
2t + 3(1.50) = 6.90
2t + 4.5 = 6.90
2t = 2.4
t = £1.20