Question

A builder has some red and grey bricks. The red bricks weigh 3 kilograms each, and the grey bricks weigh 2 kilograms each. If the total weight of all 7 bricks is 17 kilograms, how many of each type of brick does Omar have?
?=red bricks

?=grey bricks

you have to guess and check word problems
I have to finish the sums by today

Answer 1

Answer:  3 red bricks and 4 grey bricks

Step-by-step explanation:

You have 17 kg total with weights of 3 kg and 2 kg.

Since 17 is an odd number, subtract one 3 kg weight to get an even #.

17 - 1(3 kg) = 14      

14 ÷ 2 kg = 7

One 3 kg weight results in seven 2 kg weights = 8 total weights.

Since the given problem states that there are only seven weights, my guess was not correct.

Try Again:

Since we need and odd number of 3 kg weights, try three 3 kg weights

17 - 3(3 kg) = 8

8 ÷ 2 kg = 4

Three 3 kg weights and four 2 kg weights = 7 total weights. $\checkmark$

Note that this can be solved mathematically using a system of equations:

Weight: 3r + 2g = 17

Quantity: r  +  g =  7