Workspace Units: MM, use the front plane

Step 1) Create 2 line segments, centered at the origin (as always) and dimension them to 10 MM each

step 2)  These should be angled at 45 degrees

Step 3) Add a 12 and 9 MM segments :

Step 4)  Dimension the 2 angles to 140:

step 5) Connect with a tangent arc

Step 6)  Add a 5 MM symmetric extrude

Step 7)  Fillet the Edge of Extrude 1 in these 3 places:

Step 8)  Final Filletted version: