Answer : The equation could you use to find p is, 
Step-by-step explanation :
Let the cost of 1 pen be, 'x'
and the cost of 1 pencil is, 'p'
As we are given that total cost of 1 pen and 1 pencil is $2.10. The equation will be:
............(1)
And we have also given that the pen costs twice as much as a pencil. The equation will be:
............(2)
Now put the equation 2 in equation 1, we get:


Thus, the equation could you use to find p is, 
27
you multiply .30 times 90 and you get 27
Answer: 12 pounds.
Step-by-step explanation:
To solve this question, we'll use the direct proportion which is.
y = kx
Where,
y = weight on moon = 48 pounds
x = weight on Earth = 300 pounds
k = Unknown
y = kx
48 = 300k
k = 48/300
k = 0.16
The weight that a 75 pound object on Earth would weigh on the moon will be:
y = kx
where,
y = weight on moon = Unknown
k = 0.16
x = weight on Earth = 75 pounds
y = kx
y= 0.16 × 75
y = 12 pounds
The weight on the moon will be 12 pounds.
Their total expenses are ...
.. $1.50 +3.00 +1.25 = $5.75
Their profit is the difference between their charge and their cost:
.. $25.00 -5.75 = $19.25
The correct choice is ...
B) $19.25