Mathematics for IGCSE & O level - Ratio And Proportion (Section 1 - No. 7)
The ratio of cement to sand in a mixture is 1:4. If 20 kg of cement is used, how many kg of sand is needed?
5 kg
20 kg
80 kg
100 kg
解释
Cement:Sand=1:4. 20 = 1*20, so sand is 4*20=80