can i please get help on this word problem

Question

2 kg of sugar and 5 kg of maize meal cost N$ 41.3 kg of sugar and 10 kg of maize meal cost N$ 74.50. How much does 12 kg bag of maize meal cost?

Answer 1

Let S=cost per kg of sugar and M=cost per kg of maize meal.

2S+5M=41; 3S+10M=74.50.

So 4S+10M=82. But 10M=74.50-3S so 4S+74.50-3S=82; S+74.50=82 and S=82-74.50=7.50.

Now we can work out M: 5M=41-2S=41-15=26, making M=26/5=N$5.20.

So 12kg of maize meal costs 12*5.20=N$62.40.