The total mass of 7 big sacks of sugar and 2 small sacks of sugar is 94 kg. The total mass of 3 big sacks of sugar and 3 small sacks of sugar is 51 kg. Find the mass of 1 big sack of sugar.

2 answers

7b + 2s = 94

3b + 3s = 51

Multiply first equation by 3.

21b + 6s = 282

Multiply second equation by 2.

6b + 6s = 102

Subtract second equation from first. I'll let you take it from here.
3 big sacks + 3 small sacks→51kg
1 big sack + 1 small sack = 51 kg ÷ 3 = 17 kg
2 big sacks + 2 small sacks → 2 × 17 kg = 34 kg 5 big sacks → 94 kg – 34 kg = 60 kg
1 big sack → 60 ÷ 5 = 12
The mass of 1 big sack of sugar is 12 kg.