Question

Lalit earns Rs x per day and spends Rs y per day. How much does he save in 30 days?

Answer 1

Lalit's earning per day = Rs x
∴ Lalit's earning in 30 days = Rs 30 $\times$x
= Rs 30x

Similarly, Lalit's expenditure per day = Rs y
∴ Lalit's expenditure in 30 days = Rs 30 $\times$ y
= Rs 30y
∴ In 30 days, Lalit saves = (Total earnings $-$ Total expenditure)
= Rs (30x $-$ 30y)
= Rs 30(x - y)