Let the cost of the hair dryer equal x.
The net cost plus a 40% markup equals 42, set up an equation and solve forex.
1.4x = 42
Divide both sides by 1.4
X = 42 / 1.4
X = 30
The net cost was £30
Given:
Monthly fees for the local pool are $8 per month and $2 per visit.
Hector pays $34 in pool fees total for the month.
To find:
The number of times he visit the pool.
Solution:
We have,
Monthly fee of pool = $8
Additional fee = $2 per visit
Let Hector visit x times.
Additional fee for x times = $2x
Total fee = Monthly fee + Additional fee



Divide both sides by 2.


Therefore, Hector visit the pool 13 times.
To find it, evaluate it at the endpoints and the vertex
in form
f(x)=ax²+bx+c
the x value of the vertex is -b/2a
given
c(t)=1t²-10t+76
x value of vertex is -(-10)/1=10
evaluate c(0) and c(13) and c(10)
c(0)=76
c(13)=115
c(10)=76
it reached minimum in 2000 and 2010
porbably teacher wants 2010
the min value is $76