Answer:
(L-a)/d + 1 = n
Step-by-step explanation:
Let's isolate (n-1), and after that isolate n:
1) subtract a from both sides: L - a = (n-1)d
2) Divide both sides by d: (L-a)/d = n-1
3) Add 1 to both sides, to isolate n: (L-a)/d + 1 = n
Step-by-step explanation:
According to this description we need a number that can be divided by 2,3 and 4 since the amount of rocks can be described by a natural number. However if a number is divided by 4 it is divided by 2 as well since 2*2=4.

If α is a natural number then 2*α is a natural number as well as the product of two natural numbers.
Which means that we need a number devided by 3 and 4.
The smallest number that fulfills this demand is 3*4=12.
Also any product of 12 with any natural number can be devided by 3, 4 and 2.
If the exercise asks for the numbers that are divided only by 2,3 and 4 these are:

Answer:
7
Step-by-step explanation:
=(7-3)+6÷2
=(7-3)+3
=4+3
=7
Answer:
56 inches
Step-by-step explanation:
4 feet in inches is 48
48+8=56