3. 1 zi = 20/100 • × =20×/100 =2×/10=1×/5
au rămas : x-1×/5 = 5×/5 - 1×/5 = 4×/5
2 zi = 25/100 • 4x/5 = 5×/25 = 1×/5
au rămas 4x/5 - 1×/5 = 3×/5
3 zi = 9
3×:5=9
3×=45
× = 45:3
× = 15 km
4. (x+7)/3 + (×+4)/2-(2×+5)/3 = (5×-2)/4
4×+28 + 6×+24 - 8×+20=15×-6
4×+6×-8×-15×=-28-24-20+6
10×-23×=-92+6
-13×=-86 |•(-1)
13x=86
× = 86/13
