Help me plz and show work

substitute the value of y into the equation 7x+3y = 35

7x + 3(x+5) = 35 (distribute 3 through the parenthesis)

7x + 3x + 15 = 35

collect the like terms

7x + 3x = 35 - 15

10x = 20 (divide both sides by 10)

x = 2

substitute x = 2 into the equation y = x + 5

y = 2 + 5

y = 7

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.