The sum is 1625.
Answer in Words: One thousand and six hundred twenty-five.
The cube of 10 is 1000.
10 X 10 = 100 (square of ten)
100 x 10 = 1000 (cube of ten)
The square of 25 is 625.
25 x 25 = 625 (square of 25)
Therefore, 1000 + 625 = 1625
the sum is 1625
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, 
Seems like you already have the answer so peace