Please help I need the answer ASAP!!! Which function represents exponential decay?

f(x) = One-half(2)x

f(x) = Three-fourths(Negative one-fifth)x

f(x) = 3(Seven-halves)x

f(x) = 2(Two-thirds)x

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.