Biology A level maths question

Can seem to figure this out, can anyone help?

The two DNA strands of a particular gene contain 168 guanine bases
between them. The relationship between the numbers of guanine bases
(G), adenine bases (A), thymine bases (T) and cytosine bases (C) in these
two strands of DNA is shown in the following equation.
G = 4(A + T) – C
Use this information and your understanding of DNA structure to calculate
the maximum number of amino acids coded by this gene.
Show your working

Thank you!!

Ok so C and G are complimentary so will both equal 168
168=4(A+T)-168
A and T are complimentary so I solved the equation in terms of X
168= 4(2x)-168
Add 168 to both sides and multiply 2x by 4
336=8x
Then divide by 8 so x=42 meaning A=42 and T=42

Then if you add all the bases you get 420 but dna replication uses only one strand as a template so divide it by 2 to get 210
Finally amino acids have 3 bases so 210/3=70 which is your final answer
Hope this helps

Hi
Sorry how did you get 420 i am just confused
Thanks