The sum of the ages of two brothers is 38. in four years ago the age of the elder brother was the square of the younger brother. Find their ages

Elder brother: 25

Younger brother: 5

Step-by-step explanation:

38 - (4+4)= 30

Now trial all square numbers

e.g 2 + 4 = 6 (does not work)

5 + (5x5)= 30

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.