You can solve this using proportion.
5 = 4
7 = ?
7(4)/5= 5.6
7 cakes cost £5.6
-$69.68 is your answer if I hope that this is correct.
1) 1 + 1 = 2
2) 1 - 1 = 0
3) 1 * 1 = 1
4) 1 / 1 = 1
Hope this helps!
The proportion equal to a/b = c/d is A.) A/C = B/D
We will know if a proportion is equivalent when its cross products are equal.
a/b = c/d where ad = bc
since ad = bc, a/c = b/d