#### Answer

Relative to an observer riding in the Stanley Steamer, the x-component of the Pierce Arrow's velocity is 50 km/h
Relative to an observer riding in the Stanley Steamer, the y-component of the Pierce Arrow's velocity is -40 km/h

#### Work Step by Step

We can write the Stanley Steamer's velocity relative to the road in component from:
$v_{sr} = 40~ \hat{j}~km/h$
We can write the Pierce Arrow's velocity relative to the road in component from:
$v_{pr} = 50~\hat{i}~km/h$
We can find the Pierce Arrow's velocity $v_{ps}$ relative to the Stanley Steamer:
$v_{pr} = v_{ps}+v_{sr}$
$v_{ps} = v_{pr} - v_{sr}$
$v_{ps} = (50~ \hat{i}-40~\hat{j})~km/h$
Relative to an observer riding in the Stanley Steamer, the x-component of the Pierce Arrow's velocity is 50 km/h
Relative to an observer riding in the Stanley Steamer, the y-component of the Pierce Arrow's velocity is -40 km/h