Răspuns:
Explicație pas cu pas:
problema 9
notam cu x drum
prima zi = 15% x = 0,15x
a doua zi = 20% x = 0,2x
a treia zi = 195 km
0,15x +0,20x + 195 = x
0,35 x +195 = x / -0,35x
195 = 0,65 x / :0,65
x = 300 km
2) (14+3)/7 +1/2-4/5 = 17/7 + 1/2 -4/5= 170/70+35/70-56/70= 149/70
3) -1,5 : 5/4 = -1,5 : 1,25 = -1,2
5)-9/4 -(-1/5 + 1/3 * 1/15) = -9/4 -(-3/15+1/3*1/15) = -9/4 -(-9/45+1/45) = -9/4 - (-8/45)= -9/4 +8/45 = -405/180 +32/180 = -373/180
4)[tex]\frac{1}{(\frac{2}{5})^{2} } +\frac{1}{2^{2} } = \frac{5^{2} }{2^{2}} + \frac{1}{2^{2} } = \frac{26}{4}[/tex]
8) 4x + 14 + 3x - 3 = 6x + 18 - 18 =>
7x +11 = 6x
x = 11
