Explanation:
3 balloons + 2 cakes = £19
=> 9 balloons + 6 cakes = £57 (multiply by 3)
9 balloons + 6 cakes = £57
- (9 balloons + 3 cakes = £42)
=> 3 cakes = £15, 1 cake = £5.
Therefore 3 balloons + 2(£5) = £19,
3 balloons = £9, 1 balloon = £3.
Hence each balloon is £3 and each cake is £5.