A measurment of a bench mark is a benchmark or line that indicates numbers
Three main methods come to mind: Substitution method, Elimination method, Matrix row-reduction.The first two methods are taught in early grades in most high schools. Matrix row-reduction is taught in senior years in high school, or more likely, in the early years of a university math or science program.
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5(5a+3)=14a-29 -- expand brackets
25a+15=14a-29 -- subtract 15 and subtract 14a from both sides
11a=-44 -- divide by 11
a=-4