(a) If

is the mass (in mg) remaining after

years, then


(b)

(c)
$540
Explanation:
7.5% of 1800 is 135
135 • 4 = 540
Answer:
Length = 12cm
Step-by-step explanation:
The dimensions of the recatngle is:
- width → x
and
- length → x+7
The area of a rectangle follows the formula: length*width
Meaning: x * (x + 7) = 60
Expand that: x^2 + 7x = 60
Rearragne the equation and factorise it
(x-5)(x+12) = 0
The width cannot be a negative value, so the answer must be 5.
Remember that x was the width and the length is the width add the 7.
So the length is 12 cm.
Alright, lets gets started.
I suppose , we are asked to find simple interest for above question.
Principal P = $1,250
Rate r = 5.7 %
Time t = 4 years
The formula for simple interest = 
Hence simple interest 
Simple interest 
Simple interest = 285 $
Hence interest earned is $ 285. : Answer
Hope it will help :)