Write in scientific notation .0000345

I know how to do it I'ma explain it step by step.

Step-by-step explanation:

Move the decimal so there is one non-zero digit to the left of the decimal point. The number of decimal places you move will be the exponent on the 10 . If the decimal is being moved to the right, the exponent will be negative. If the decimal is being moved to the left, the exponent will be positive.

7 girls

Step-by-step explanation:

The ratio of boys : girls = 7 : 1 = 7x : x ( x is a multiplier )

There are 42 more boys than girls, thus

7x = x + 42 ( subtract x from both sides )

6x = 42 ( divide both sides by 6 )

x = 7

Hence

there are 7 girls

and 7x = 7 × 7 = 49 boys