(a)[1]
Simplify the expression $a + 4a - 3a$.
(b)[1]
Simplify the expression $8b - 4 \times 7b$.
(c)[4]
The perimeter of this shape matches the perimeter of a square. Find an expression for one side of the square. Give your answer in its simplest form.
(d)[6]
Write down a pair of simultaneous equations, then solve them to determine the cost of one cup of tea and the cost of one cake. You must show all your working.