Question: \[7\left( {x - 3} \right) = 10 - 2\left( {x + 2} \right)\] Solution:
\(9x = 21 - 4\) (line 2)
\(9x = 37\) (line 3)
\(x = \frac{{37}}{9}\) (line 4)
\(x = 4\frac{1}{9}\) (line 5)
- You open bracket correctly.
(You expanded correctly for line 1.) - You are careless.
(You are careless at line 3, you have substracted wrongly.) - Don’t skip steps.
(Between line 1 and 2, you should write out the working \(7x + 2x = 10 - 4 + 21\).) - You bring over the \(21\) correctly.
(You bring over the \(21\) correctly in line 2.) - Where is the \(10\)?
(The \(10\) in line 2 is missing in line 3.) - It should be \(17\) not \(37\).
(It should be \(17\) not \(37\) in the 4th line.) - Good!
("Elaborate why and where it is done well")
