Mass box a = 10 grams; mass box b = 5 grams; mass box c—made of one a and one b

how much a and b would be needed to produce 30 grams of c? g of a; g of b.

Mass box A = x = 10 grams

Mass box B = y = 5 grams

Both together = 10 + 5 grams = 15 grams

Let the mass of the box C be z.

Mass box C contains One mass box A + one mass Box B .

i.e.,

z = x + y

Given z = 30 grams

For, x = 10 and y = 5

30 = 10 + 5

30 = 15

Unbalanced.

For, x = 20 and y = 10

30 = 2 (10) + 2 (5)

30 = 20 + 10

30 = 30

Balanced.

30grams = 20grams +10 grams

So, 20 g of A and 10g of B  would be needed to produce 30 grams of C (Answer)

the answer your looking for is c).