Search 74,136 tutors
FIND TUTORS
Ask a question
1 0

How do I solve this equation? 2[3-5(z-7)]=8(5z-8)

Tutors, please sign in to answer this question.

1 Answer

It's basically a straightforward order of operations question, with a lot of nested parentheses (ie, parentheses within parentheses) to confuse you.  With nested parentheses, always start from the innermost.
 
2[ 3 - 5(z - 7)] = 8(5z - 8)
2[3 - 5z + 35] = 8(5z - 8)   [distributed -5 over the binomial (z - 7)]
6 - 10z + 70 = 8(5z - 8)   [distributed 2 over the trinomial (3 - 5z + 35)]
6 - 10z + 70 = 40z - 64   [distributed 8 over the binomial (5z - 8)]
76 - 10z = 40z - 64   [arithmetic combination of the left side]
76 = 50z -64   [added 10z to both sides]
140 = 50z   [added 64 to both sides]
2.8 = z   [divided both sides by 50]
z = 2.8   [flipped the equality around]
 
If you're having more trouble, I'm also available via Skype.  See my tutor profile for more details.

Woodbridge Linear equations tutors