Question

a) ( a x 2 ) + (a : 4 ) = 28,35
b) (a : 2 ) - ( a : 5 ) = 3,6
c) ( a : 5 ) - ( a : 8 ) < a : 7
d) ( a x 3 ) + ( a : 2 ) > 6,25
Va roooog muuult ! Ajutati-ma!

Answer 1

A) ( a x 2 ) + (a : 4 ) = 28,35
2a+a/4=2835/100
(8a+a)/4=567/20
9a/4=567/20
9ax20=567x4
a=(567x4)/(9x20)=simplif=63/5
a=12,6

b) (a : 2 ) - ( a : 5 ) = 3,6 
a/2-a/5=36/10
(5a-2a)/5=18/5
3a/5=18/5
3ax5=18x5
a=(18x5)/(3x5)=6
a=6

c) ( a : 5 ) - ( a : 8 ) < a : 7 
a/5-a/8<a/7
(8a-5a)/40<a/7
3a/40<a/7
3ax7<40a
21a-40a<0
-19a<0     inmultim -1
a>0

d) ( a x 3 ) + ( a : 2 ) > 6,25 
3a+a/2>625/100
(6a+a)/2<125/20
7a/2<25/4
7ax4<25x2
a<(25x2)/(7x4)
a<25/14