"Perimeter" is the distance all the way around the drawing. If the drawing has sides, then the perimeter is the SUM of the lengths of all the sides. It's exactly the distance an ant would have to walk along the line, to get all the way around to where he started from.
To get the perimeter of the triangle, you have to add up the lengths of the three sides.
(2a - 3) + (2a) + (3a + 1) =
2a - 3 + 2a + 3a + 1 .
Add up all the 'a's: 2a + 2a + 3a = 7a
Add up all the just plain numbers: -3 + 1 = -2
Write them together, as a binomial: 7a - 2
THAT's your expression for the perimeter.
Answer:
Let the smaller integer be x and greater integer be (x+1)
x+(x+1)=91
2x+1=91
2x=91-1=90
x=90/2
x=45
m∠R = 27.03°
Solution:
Given In ΔQRP, p = 28 km, q = 17 km, r = 15 km
To find the measure of angle R:
Law of cosine formula for ΔQRP:

Substitute the given values in the above formula.



Switch the given equation.

Subtract 1073 from both side of the equation.

Divide by –952 on both sides.



Hence m∠R = 27.03°.
240 because 2000x0.04=80 X3= 240