Question

13 si 15 va rogggg
Multumesc :****

Answer 1

13.
(4a+3a+7a+20) : 4= 40
 14a +20 = 4*40
14 a= 160 -20
14a= 140
a= 140 : 4
a=10

14.
(a+b+c) : 3 =21
(a+b) : 2=18
a=1/2*c= c/2

a+b+c= 21*3
a+b+c= 63
a+b= 18*2
a+b= 36

36 +c =63
c= 63- 36
c= 27

a=27/2
a=13, 5

b+(13,5+27)= 63
b +40,5=63
b= 63-40,5
b= 22,5


15.
(a+b) : 2= 8,(4)
(a+b): 2=76/9
a+b=76/9* 2
a+b= 152/ 9

a / b= 0,(36) = 36/99
a / b= 4 / 11
11a= 4b
a= 4b/11

4b/11+b= 152/9
36b/99+99b/99=1672/99
36b+99b=1672
135b=1672
b=1672/135
 

a= 4*1672/135 *1/11=6688/ 1485