Answer :
- Total timeof Ndiba =1+3=4hours
[tex]\boxed{\sf Distance=Speed(Time)}[/tex]
Let
- Ndibas speed be x
- Willies speed=x+10
Both travelled same distance
[tex]\\ \sf\longmapsto 4x=3(x+10)[/tex]
[tex]\\ \sf\longmapsto 4x=3x+30[/tex]
[tex]\\ \sf\longmapsto x=30mph[/tex]