What are you trying to do? You're adding x-axis position, y-axis position, and scale factors, which doesn't make sense.
You can perform a simple collision test using bounding boxes:
1. build bounding boxes for your sprites, using FloatRect:
sf::FloatRect rect;
rect.Top = sprite.GetPosition().y;
rect.Left = sprite.GetPosition().x;
rect.Bottom = rect.Top + sprite.GetSize().y;
rect.Right = rect.Left + sprite.GetSize().x;
2. Test if two bounding boxes are overlapping:
if (rect.Intersects(rect2))
{
// collision
}