1.4 + 2/5x = 3/15x - 0.8 how do you solve this?

It appears you are looking for x.
1.4+2/5x=3/15x-.08

you have to isolate the x
 first add .08 to both sides
1.48+2/5=3/15x
i would now find the equivalence fraction of 2/5 with the denominator of 15. To do this you have to multiply 5 by 3 to get 15 so, you multiply the original numerator to get the equivalent one. 2(3)=6 
1.48+6/15x=3/15x
now i am going to subtract 6/15x from both sides
1.48=  -3/15x
to get rid of the fraction i am going to convert it to a decimal.
-3/15= -.2

1.48= -.2x

now i have to divide both sides by -.2
7.4=x

You can find the area of a rectangle by multiplying the length and height. so multiply 1/2*7/4(which is the simpler version of 1 3/4) and you get 7/8 as your answer.