A good estimate of the age of the Earth is 4.54 × 10 9 years. What is this number written in standard form?

Can someone me and plz do the problem

The construction of copying qpr is started below. the next step is to set the width of the compass to the length of ab. how does this step ensure that a new angle will be congruent to the original angle? by using compass take the measures of angle and draw the same arc according to it.

The price of a lawn mower is x dollars. the store is having a 75% end of summer clearance sale. which expression can be used to find the clearance price of the mower? a) .25x b) .75x c) x - .25(75) d) x + .25(75)