a)
a - b = 110
a : b = 4 rest 20 ⇒ a = 4 × b + 20
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( 4 × b + 20 ) - b = 110
3 × b = 110 - 20
b = 90 : 3 ⇒ b = 30
a = 30 + 110 ⇒ a = 140
Verific:
140 - 30 = 110 ( diferenta )
140 : 30 = 4 rest 20
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b)
( 2 + 4 + 6 + ...... + 80 ) : ( 1 + 2 + 3 + ...... + 40 ) = 2
= 2 × ( 1 + 2 + 3 + .... + 40 ) : ( 1 + 2 + 3 + ....+ 40 ) =
= 2 × 1 =
= 2
