The ratio of the number of boys to the number of girls in a school is 4: 5 there are 95 girls in the school work out the total number of students in the school

X=number of boys
y=number of girls
(x+y)=number total of students
We can suggest the following system or equations:
x/y=4/5
y=95
Therefore:
x/95=4/5
x=(4*95)/5=76

(x+y)=76+95=171

there are 171 students in this school.

Aand b are correctly balanced reactions. they have the same number of atoms in both sides of the reaction

Yes the slope to this is -5