I need help , I don’t understand this

See the explanationExplanation:Hello! here we need to match the statements on the left-hand side to the reasons on the right-hand-side. So this is as follows:Statements:                                                       Reasons:Segment Addition Postulate                            [tex]AB+BC=AC[/tex]Substitute the given values                              [tex]5x+1+15=7x[/tex]Simplify                                                               [tex]5x+16=7x[/tex]Subtract 5x from both sides                              [tex]16=2x[/tex]Divide both sides by 2                                       [tex]16/2=2x/2[/tex]Simplify                                                               [tex]AC=7x[/tex]Substitute 8 for x                                               [tex]AC=7(8)[/tex]Simplify                                                               [tex]AC=56[/tex]So what we did here is to find the measure of segment AC by finding the x-value first. In other words, we have proven that AC = 56 by following logical arguments organized in an structured manner.Learn more:Two-column proof: