There are 10 boys and 20 girls in mrs brook's class.
mrs brook gave all the class a test.
the mean mark for all the class is 60
the mean mark for the girls is 56.
work out the mean mark for the boys.

goog may have it for you

step-by-step explanation:

first, eliminate the parenthesis:

3

x

+

2

−

4

x

second, group like terms:

3

x

−

4

x

+

2

third, combine like terms:

(

3

−

4

)

x

+

2

→

−

1

x

+

2

→

−

x

+

2

it is x equals 3   plese mark me really need it

step-by-step explanation:

option (b) is correct

step-by-step explanation:

to find the solution of this system, we need to convert it into reduced row-echelon form. we have,

after applying row operations r2 -> r2/2 and r3 -> r3/3, we get,