diff --git a/EasyLean/Basic.lean b/EasyLean/Basic.lean
index 305e1ca..f80f7c1 100644
--- a/EasyLean/Basic.lean
+++ b/EasyLean/Basic.lean
@@ -1,12 +1,8 @@
-import Mathlib.Data.Real.Basic
-import Mathlib.Tactic.Linarith
-
-theorem mathd_algebra_513
-  (a b : ℝ)
-  (h₀ : 3 * a + 2 * b = 5)
-  (h₁ : a + b = 2) :
-  a = 1 ∧ b = 1 := by
-  sorry
-
-theorem eq_four : ∀ a b c d : Nat, a = b → a = d → a = c → c = b := by
-  sorry
+import EasyLean.MathdAlgebra.mathd_algebra_513
+
+namespace EasyLean
+
+export MathdAlgebra (mathd_algebra_513)
+
+end EasyLean
+
diff --git a/EasyLean/MathdAlgebra/mathd_algebra_513.lean b/EasyLean/MathdAlgebra/mathd_algebra_513.lean
new file mode 100644
index 0000000..62bf32a
--- /dev/null
+++ b/EasyLean/MathdAlgebra/mathd_algebra_513.lean
@@ -0,0 +1,14 @@
+import Mathlib
+
+namespace EasyLean
+namespace MathdAlgebra
+
+theorem mathd_algebra_513 (a b : ℝ)
+    (h₀ : 3 * a + 2 * b = 5)
+    (h₁ : a + b = 2) :
+    a = 1 ∧ b = 1 := by
+  constructor <;> linarith [h₀, h₁]
+
+end MathdAlgebra
+end EasyLean
+
diff --git a/Main.lean b/Main.lean
new file mode 100644
index 0000000..246c449
--- /dev/null
+++ b/Main.lean
@@ -0,0 +1,6 @@
+import EasyLean
+
+open EasyLean
+
+#check mathd_algebra_513
+