I think this is more of an opinion question. What someone could solve mentally may not be the same as someone else's.If it were my worksheet, I'd circle all of them but it may be different for you.
At your level, I'd probably circle:
54 - 10
93 - 20
and 39 - 2
Y= 210 you have to distribute 2/3 to y then to 57 and your equation would be 2/3y + 38= 178 then you take 38 and subtract 178 - 38 and you get 140 then you divide 140/ (2/3) and you will get 210 as your answer.(:
So since they are similar
AC/BC=CD/CE
so
(66-x)/30=(x+4)/5
times both sides by 5
(66-x)/6=x+4
times both sides by 6
66-x=6(x+4)
distribute
66-x=6x+24
add x to both sides
66=7x+24
minus 24 from both sides
42=7x
divide both sides by 7
6=x
x=6 units
First you gotta do rise over run. then once you do that, you should get your answer. which is x=-4
