15 litres of a 40% sugar syrup are mixed with 25 litres of a 20% syrup. What is the strength of the mixture?

Explanation

1. 01

   Sugar: $0.4 \times 15 + 0.2 \times 25 = 6 + 5 = 11$ litres in 40 litres.

2. 02

   $\frac{11}{40} \times 100 = 27.5\%$.