# Aparticular computer takes 43 nanoseconds to carry out five sums and seven products. it takes 36 nanoseconds

Aparticular computer takes 43 nanoseconds to carry out five sums and seven products. it takes 36 nanoseconds to carry out four sums and six products. how long does the computer take to carry out one sum? to carry out one product?

## This Post Has 3 Comments

1. gudtavosanchez19 says:

This is the concept of simultaneous equations:
Let the time taken to do one sum be x and time taken to do one product be y.
Total time taken to do 5 sums and seven products will be:
5x+7y=43

Total time taken to do 4 sums and 6 products will be:
4x+6y=36

This gives us the simultaneous equations:
5x+7y=43
4x+6y=36

multiply the top equation by 4 and the bottom equation by 5 then subtract the bottom equation from the top gives us:
-2y=-8
thus:
y=4
next
multiply the top equation by 6 and the bottom equation by 7 then subtract the bottom from the top equation gives us:
-2x=-6
hence;
x=3
therefore:
Total time taken to do 1 sum is x=3 nanoseconds
Total time taken to do 1 product is y=4 nanoseconds

2. 2016gbryant says:

A) 5s + 7p = 43 nanoseconds
B) 4s + 6p = 36 nanoseconds
Multiply equation A) by 4 and equation B) by -5

A) 20s + 28p = 172
B) -20s -30p = -180  Adding both equations
-2p = -8
EACH product requires 4 nanseconds

Computing SUM
A) 20s + 28*4 = 172
A) 20s + 112 = 172
A) 20s = 60
SUM = 3 nanosecond

3. jasminen3835232 says:

Sums→x
Products→y

Computer takes 43 nanoseconds to carry out five sums and seven products: 5x+7y=43
It takes 36 nanoseconds to carry out four sums and six products: 4x+6y=36

5x+7y=43
4x+6y=36⇒4x=36-6y

5x+7y=43
x=9-1.5y

5*(9-1.5y)+7y=43⇒45-7.5y+7y=43
x=9-1.5y

0.5y=2⇒y=4
x=9-1.5*4⇒x=3

Computer takes 3 nanoseconds to carry out one sum and 4 nanoseconds to carry out one product.