Question

How to get to the correct answer, it is the second question on the sheet

Answer 1

Given for the second question on the sheet:

One loaf of bread and six rolls cost $1.80

Let the cost of one loaf of bread = x

Let the cost of one roll = y

So,

$\begin{gathered} x+6y=1.80 \\ x=1.80-6y\rightarrow(1) \end{gathered}$

And Two loaves of bread and four rolls cost $2.40

So,

$2x+4y=2.40\rightarrow(2)$

substitute with (x) from equation (1) into equation (2) then solve for (y)

$\begin{gathered} 2(1.80-6y)+4y=2.40 \\ 3.60-12y+4y=2.40 \\ -8y=2.40-3.60 \\ -8y=-1.20 \\ y=\frac{-1.20}{-8}=0.15 \end{gathered}$

substitute with (y) into equation (1) and solve for x:

$\begin{gathered} x=1.80-6\cdot0.15 \\ x=1.80-0.90 \\ x=0.90 \end{gathered}$

So, the answer will be:

The cost of one loaf of bread = $0.90