BECE Mathematics 2019 Paper

Let $x=$ amount for selling the 90 oranges$\;3=0.75$$\;90=x$Cross multiply. Left side multiplying right and right side multiplying left$3 \times x=90 \times 0.75$Divide both sides by 3$\; \frac{3 \times x}{3}= \frac{90 \times 0.75}{3}$$\; x=\frac{90 \times 0.75}{3}$Change the decimal to the format, whole number $\times 10^{a}$$0.75=75 \times 10^{-2}$ (When you move the decimal point to the right its negative to the number of times you moved)$\Rightarrow x=\frac{90 \times 75 \times 10^{-2}}{3}$3 goes into 90, 30 times$\; x=30 \times 75 \times 10^{-2}$$\;30 \times 75=2250$$\; \Rightarrow x=2250 \times 10^{-2}$Now change the whole number $\times 10^{a}$ format back to decimalSince the power in $10^{-2}$ is negative 2 , you have to move the decimal point to the left two times $2250=2250.0$ (Every number has .0 which is not written)$\;2250.0 \times 10^{-2}=22.50$$\; \Rightarrow x= \text{GH₵} 22.50$