Step-by-step explanation:

Question attached
Answer:
130
Step-by-step explanation:
Number of students old donors can be calculated from the Pareto chart by adding number of blood donors on the different bars:
Type 0= 50
Type A= 35
Type B =30
Type AB =15
Therefore 50+35+30+15=130 blood donors
Answer:
I don't really know but one triangle is 180 degrees so two added together is 360 degrees...
but ohh I remembered
a=c+d (since a+b=180 and c+d+b=180)
e=g+h (since e+f=180 and g+h+f= 180)
and the fact is that c+d+g+h+b+f=the angle sum of quadrilateral PQRS
a+e+b+f= the angle sum of quadrilateral PQRS (by substitutions)
a+e+b+f=360 (four angles are from one origin so it's 360 degrees )
Simplify the expression

It can be simplified as below:
